This year a group of residents decided to investigate circulating the water with a pump, and using solar photovoltaics to provide the power — and stop wasting water.
A few months ago I ordered the parts and the small team of volunteers has just recently put the components together and got it all working! You can almost see the water flowing in the photo of the fountain with its solar panel.
I thought it would be interesting to document some of the things we learned while installing this system.
See the diagram below for the layout of components (and don’t laugh at my crude representation of a fountain). The first step the volunteers worked on was mounting the solar panel and getting the wires run under the ground to a lockable hatch where the other components were kept (out of the rain).
The next step was to do a brief test of the battery connected to the pump and with the solar panel connected to the pump. The two safety precautions taken were: 1) fuse in line with the positive connection to the battery (so any inadvertent short would blow the fuse and not hurt the pump or battery), and 2) an overheat protection device on the pump in case the pump gets clogged or stalls, it will shut down to protect the motor. If you try to turn a motor that is stuck, you can burn out the motor pretty quickly.
Connecting the solar panel directly to the pump proved that the pump was working and the solar panel could provide enough power to turn it. But when connecting the battery directly to the pump we blew the fuse (actually more than one). When a motor starts up and is given as much battery power as it wants, the start up current surge can be quite high and was probably causing the blown fuses.
We decided to add the solar charger to the battery/fuse circuit and then to the pump with the theory that the charger is providing some current regulation and might absorb the start up surge. It did and we were able to prove that the battery/charger could turn the pump on.
The final step was to add a shut off switch to turn off the pump when it dark, and back on when it is light. That way we aren’t relying on the battery alone to turn the pump. The battery is not large enough capacity to run the pump much longer than about 12-16 hours without recharging.
The volunteers were so excited that it was working, that they decided not to add the switch right away. That meant the pump continued to pump 24 hours a day (with or without sun) until the battery completely died — which it did after 4 days and 3 nights. Not bad… but now they are ready to add the shut off switch!